1. Field of the Invention
The present invention relates to an improved grip especially adapted for use on golf clubs and a method of manufacturing golf club grips.
2. Description of the Prior Art
Grips having a wide variety of different construction have been fabricated for use as golf club grips over the years. The shaft of a golf club is an elongated, narrow cylindrical structure which may be formed of solid wood, a solid metal rod, or hollow metal tubing which may be a composite formed of carbon graphite or steel. The extremity of the shaft of the golf club which is held by a golfer is typically quite narrow, usually no more than about five eighths of an inch in diameter at the most. The golf club shaft is normally quite smooth, so that a grip of some type is essential to allow the golfer to control the swing of the club.
Golf club grips having a wide variety of configurations and structure have been employed over the years. Some golf club grips are formed by strips of some outer material, such as leather, overwound about some packing material to extend along the upper end of the shaft of the club for a distance of about ten to twelve inches. Other golf club grips are formed of a single material secured about the upper extremity of the shaft of the golf club. Still other grips are formed of several different materials, arranged in layers on the end of the shaft of the golf club.
The construction and physical characteristics of a golf club grip are extremely important, since minuscule variations in the physical characteristics of a golf club grip will produce very pronounced effects upon the accuracy of golf shots. One of the physical characteristics which is extremely important in a golf club grip is the stiffness, which is the modulus of elasticity of a material or materials of which the golf club grip is fabricated This parameter is extremely important due to the torsional forces which are exerted on the grip as a golfer executes a swing and strikes a golf ball.
As the golfer holds the golf club grip and brings the golf club through a swing, the golfer's hands exert a torsional force on the structure of the grip which acts essentially tangential to the axis of the golf club shaft. The torsional forces on a golf club grip during execution of a swing are transmitted from the surface of the grip radially inwardly to the structure of the golf club shaft. However, the extent to which these torsional forces are transmitted to the shaft do vary, depending upon the stiffness of the structure of the golf club grip. A very rigid or stiff grip will transmit almost the entire torsional force applied to the grip by the golfer's hands to the golf club shaft. On the other hand, if the same torsional force is applied to a very soft grip, much of the torsional movement will be absorbed in the structure of the grip in resiliently deforming the grip within the limits of its elasticity.
A very substantial portion of torsional force applied to a golf club grip fabricated of soft, resiliently deformable materials will be absorbed in twisting the outer surface of the grip relative to the interface between the grip and the golf club shaft. This reduces the amount of torsional force applied to the golf club shaft. Thus, even slight differences in the stiffness characteristics of different golf club grips will affect the extent to which a golf club shaft is rotated about its own axis during execution of a golf swing. These differences are extremely important since the extent to which the club shaft is rotated about its own axis affects the angle at which the generally planar face of the golf club head strikes a golf ball. A very tiny change in the angle of impact of the golf club head against the golf ball results in a very large deviation in the location where the ball ultimately comes to rest.
Another way in which the stiffness of the material of a golf club grip affects the flight of a golf ball resides in the extent to which the torsional force exerted by the hands of the golfer is transmitted to the structure of the grip. The hands of a golfer are much more likely to slip slightly in rotation around the axis of a golf club shaft when the golf club grip employed is very rigid and stiff and has a smooth outer surface. The coefficient of friction between the golfer's hands and such a grip is less than is the case when a golfer employs a grip that is much softer. As a result, a greater portion of torsional force exerted by a golfer's hands on a golf club grip is transmitted to the outer surface of a soft, resilient golf club grip which has lower stiffness characteristics than a more rigid grip. On the other hand, more of the torsional force is absorbed within the structure of such a soft grip itself due to the relatively large degree of resilient deformation of the structure of the grip that occurs during the golf swing.
To maximize the degree of control which a golfer can exert in executing a swing of a golf club, it is desireable for the internal structure of the grip to have a high degree of stiffness, but for the exterior surface of the grip to exhibit a high coefficient of friction. These mutually conflicting characteristics have required golf club grip manufacturers to make compromises which detract from the degree of control of a golf swing achieved by a golfer using conventional golf club grips.